A fermented plant milk composition of chestnut and walnut protein: focusing on the effects of different strains on physicochemical properties and flavor

This study developed a fermented plant milk based on chestnut and walnut protein using single and mixed lactic acid bacteria (LAB) fermentation. The physicochemical properties and flavor profiles of the resulting products were systematically compared. The results demonstrated that fermentation with a selected co-culture of Lactobacillus rhamnosus and Lactobacillus casei induced significant biochemical changes. The pH decreased from 5.35 to 3.61, while titratable acidity increased from 22.5 to 70 °T. Notably, the fermentation process significantly enhanced antioxidant activity, with 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity rising from 41.85% to 61.44% and ferric reducing antioxidant potential increasing from 0.96 to 1.71 μmol/mL. The viable LAB counts in the co-fermented sample reached 1.42 × 10 9 CFU/mL. A total of 64 volatile compounds were identified by gas chromatography–ion mobility spectrometry (GC-IMS), including 13 aldehydes, 12 alcohols, 12 ketones, 12 esters, 1 acid and 14 others, with 36 additional volatile compounds formed after fermentation, which markedly enhanced the flavor profile of the product. These findings offer valuable theoretical and practical insights for the development of chestnut-based functional dairy alternatives. • A fermented plant milk composition of chestnut and walnut protein was developed. • A novel probiotic combination of L.R + L.C enabled plant chestnut milk. • The chestnut matrix with final viability reached 1.42 × 10 9 CFU/mL. • A total of 64 volatile compounds were by GC-IMS. • The content of 36 flavor compounds increased after fermentation.